Indirect evidence that guarded quiescent deutonymph females invest energy to attract conspecific males in the Kanzawa spider mite (Acari: Tetranychidae)?

Abstract

Because only the first mating results in fertilization in Tetranychus kanzawai (Acari: Tetranychidae), adult males guard quiescent deutonymph females (i.e., precopulatory mate guarding). A previous study reported that quiescent deutonymph females guarded by a male attract more conspecific males than solitary females and then hypothesized that guarded females release more chemical signals than solitary ones to attract males. Quiescent deutonymph females do not feed. If the hypothesis is appropriate, guarded females should invest energy in attracting males at the expense of investment in other activities, such as egg production. Therefore, we compared oviposition rates immediately after adult emergence between guarded females and solitary females. On the first day, the oviposition rate of guarded females was lower than that of solitary females. On the second day, however, there was no significant difference between female groups. These results suggest that guarded females invest energy in activities other than egg production before adult emergence and that the energetic cost is easily recoverable. We believe that our finding indirectly supports the hypothesis that guarded females release more chemical signals than solitary females to attract conspecific males.